The invention relates to an electronic control unit for a motor vehicle, in particular for an automatic motor vehicle transmission. The control unit has a circuit support made of a temperature-resistant ceramic material on which electrical or electronic components of the control unit are disposed. In addition, there is a temperature sensor for detecting a temperature of an environment to be taken into consideration and the sensor is connected to an evaluation circuit.
Modern electronic control units in automotive engineering are increasingly constructed directly on or in the apparatus to be controlled. Thus, for example, electronic transmission control units within an automatic transmission are built into the oil sump or injection oil region or are built onto the transmission casing as disclosed in Published European Patent Application EP 0 758 726 A2. Engine control units are built onto the engine or the intake tract, for example. In order to control the apparatuses, it is frequently necessary to detect the apparatus temperature or the temperature of a surrounding medium (for example the transmission oil temperature).
In the case of a known transmission controller built onto the casing of the transmission, a separate temperature sensor is mounted on an electronic assembly. However, the transmission controller is not immersed in the transmission oil, its electronic assembly is only connected by a duct to a region of the transmission that contains transmission oil. Such a controller is disclosed in German Utility Model DE 295 13 950 U1.
An advanced transmission control unit is disposed within the transmission casing as disclosed in German Utility Model DE 93 07 228 U1, the necessity for accurate temperature measurement not being discussed in that case. Another known control unit is disposed on the intake tract of a motor vehicle engine as disclosed in German Patent DE 96 11 024 C1. The heat loss from power components is effectively dissipated by a strong stream of air, but the temperature of the intake air is not measured.
It is accordingly an object of the invention to provide an electronic control unit for a motor vehicle which overcomes the above-mentioned disadvantages of the prior art devices of this general type.
With the foregoing and other objects in view there is provided, in accordance with the invention, an electronic control unit for a motor vehicle, including:
a circuit support made of a temperature-resistant ceramic material, the circuit support to be thermally conductively connected to a surrounding medium;
electrical/electronic components disposed on the circuit support;
an evaluation circuit; and
at least one resistive track made of a material having a temperature-dependent electrical resistance applied onto the circuit support and connected to the evaluation circuit, the evaluation circuit determining a temperature of the surrounding medium using resistance values measured on the at least one resistive track.
The invention is based on the technical problem of providing, with a low outlay, a control unit that enables an accurate temperature measurement and is particularly suitable for being built into a transmission casing or into the intake tract of a motor vehicle engine.
The particular advantages of the invention are that it yields a cost-effective construction technology for the integration of a temperature sensor into an electronic control unit.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in an electronic control unit for a motor vehicle, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.